Marine, navy, army - the mentality is pretty much the same, if you ask me. The haircut is, anyway.
Army mentality: Basic foot troops, average attitude varies on MOS
Navy mentality: Overly technological/logical
Marine mentality: Fucking,
psychotic. These guys will do anything, and be nuts while doing it (Before someone says I'm insulting Marines, I got this from a guy who used to be a LCpl in the USMC as a Designated Marksman). Basically they're badasses and they know it.